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Neuro 600 > Somatic Motor Pathways > Flashcards

Somatic Motor Pathways Flashcards

1
Q

Motor portions of cerebral cortex

A

Initiate and control precise movements

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2
Q

Basal ganglia

A

Establish muscle tone and integrate semivoluntary automatic movements

Inhibits unwanted movement

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3
Q

Cerebellum

A

Smooth out movements; maintain posture and balance

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4
Q

Lower motor neurons

A

Extend from brain stem or spinal cord, through spinal or cranial nerves, to skeletal muscles
AKA final common pathway

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5
Q

Why are LMNs also called Final Common Pathways

A

Because many regulatory mechanisms converge on these peripheral neurons

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6
Q

How to UMNs extend from brain to LMNs?

A

Direct and indirect pathways

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7
Q

Direct pathway

A

AKA pyramidal pathways
Cerebral cortex through spinal cord and out to muscles
Voluntary

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8
Q

Indirect pathways

A

Provide input from basal nuclei, cerebellum, and cerebral cortex

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9
Q

Four components of Somatic Motor Pathways

A
  1. local circuit neurons
  2. upper motor neurons
  3. basal nuclei neurons
  4. cerebellar neurons
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10
Q

Local Circuit Neurons

A

Interneurons.
Receive input from somatic sensory receptors and from higher centres in brain.
Help coordinate rhythmic activity in specific muscle groups

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11
Q

Upper Motor Neurons

A

Communicate with both local circuit neurons (mostly) and LMNs
UMN from cerebral cortex essential for voluntary movements
Others originate in motor centres of the brain stem

Influenced by basal nuclei and cerebellum

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12
Q

Motor centres of brain stem

A

Red nucleus
Vestibular nucleus
Superior colliculus
Reticular formation

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13
Q

UMNs from the brain stem regulate

A

Muscle tone
Postural muscles
Balance
Orientation of the head and body

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14
Q

Basal nuclei neurons

A

Assist movement by providing input to UMN
Interconnected with cerebral cortex (via thalamus) and brain stem.
Initiation and termination of movements
Suppress unwanted movements
Establish muscle tone

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15
Q

Cerebellar Neurons

A

Control activity of UMN
Interconnected with cerebral cortex (via thalamus) and brain stem
Monitors difference between intended movements and actual movements, then corrects
–> coordinates movements and helps maintain posture and balance

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16
Q

What percentage of fibres decussate at pyramid?

A

90%

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17
Q

Lateral Corticospinal Tract

A

The 90% of Corticospinal fibres that decussate.

Control muscles for fine precise and highly skilled movement.

Synapse with LMN in anterior grey horn

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18
Q

Anterior Corticospinal Tract

A

10% of the axons that don’t decussate in the medulla.

Movement of neck and trunk
Coordination of axial movement

Cross over at level of LMN synapse

Synapse with LMN or internet ribs in anterior grey horn

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19
Q

Corticobulbar Tract

A

Control skeletal muscles of head

Cerebral cortex –> descend through internal capsule of cerebrum and cerebral peduncle of midbrain –> motor nuclei of CN 3, 4, 5, 6, 7, 9, 10, 11, 12.

Control precise, voluntary movement of eye, tongue, neck; swallowing, chewing, facial expression, speech.

Some decussate. Some don’t.

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20
Q

Primary Motor Cortex

A

Precentral gyrus

Plan and initiate voluntary movement

21
Q

Flaccid paralysis

A

Damage to LMN
Voluntary movement
Ipsilateral
No reflex action

22
Q

Spastic paralysis

A

Damage to UMN
Contralateral
Exaggerated reflex

23
Q

Indirect pathways

A

All somatic motor tracts except corticobulbar and corticospinal

Involve motor cortex, basal ganglia,thalamus, cerebellum, RAS

24
Q

Five indirect tracts

A 
Rubrospinal
Tectospinal
Vestibulospinal
Lateral reticulospinal
Medial reticulospinal
25
Q

Rubrospinal tract

A

Extrapyramidal/indirect tract

Red nucleus –> CL skeletal muscle
Precise movements of distal upper limb; muscle tone.

26
Q

Tectospinal tract

A

Indirect/extrapyramidal

Superior colliculus –> CL skeletal muscle

Movement of head and eyes in response to visual stimuli.

27
Q

Vestibulospinal Tract

A

Indirect/extrapyramidal

Vestibular nucleus (CN VIII) in medulla to ipsilateral muscles

Balance in response to head movement

28
Q

Lateral reticulospinal

A

Extrapyramidal/indirect

RAS –> increase flexor reflexes, inhibit extensor reflexes, decrease axial and proximal limb muscle tone

29
Q

Medial reticulospinal

A

Extrapyramidal/indirect

RAS –> increase extensor reflexes, inhibit flexor reflexes, increase axial and proximal limb muscle tone

30
Q

Final response of skeletal muscle determined by

A

Sum total of inhibitory and excitatory signals coming from all the UMN.

31
Q

Sleep and wakefulness are controlled by

A

Reticular activating system

32
Q

RAS is activated by what types of

I put

A

All sensory except olfaction.

33
Q

Circadian rhythm is determined by the

A

Hypothalamus

34
Q

Sleep has how many stages

A

Five

Four nonREM/slow wave + one REM

35
Q

Stage 1 of sleep

A

Drifting to sleep

Hypnic jerk occurs then

36
Q

Stage 2 of sleep

A

Fragments of dream

Eyes roll side to side

37
Q

Stage 3 of sleep

A

Very relaxed. Moderately deep.

BP and T° drop.

38
Q

Stage 4 of sleep

A

Deep sleep

Bedwetting, sleep walking

39
Q

REM sleep

A

Most neural activity and O2 use.

Most dreams occur

40
Q

Plasticity

A

The capacity for the brain to change with learning.

41
Q

Intermediate memory

A

Recall for a few seconds

42
Q

Short term memory

A

Seconds to hours

Electrical and chemical

43
Q

Long term memory

A

Days to years

Anatomical and biochemical changes

44
Q

Anterograde amnesia

A

Inability to create new memories

45
Q

Retrograde amnesia

A

Inability to recall memories from before the event.

46
Q

Damage to basal ganglia

A

Uncontrollable abnormal body movement

Possible muscle rigidity and tremors

Parkinson’s. Huntington.

47
Q

Cortex –> basal ganglia –> thalamus –> cortex circuit

A

Initiates and terminates movement.

48
Q

Basal ganglia –> reticular formation

A

Reduces muscle tone

49
Q

Four aspects of cerebellar function.

A
  1. Monitoring movement intent (command signals from motor cortex and BN via pons)
  2. Monitoring actual movement (sensory info)
  3. Comparing 1 & 2
  4. Correcting as necessary (via thalamus to cerebral cortex)

Neuro 600 (6 decks)

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